Refrigerating apparatus



8, 1950 R. s. GAUGLER 2,517,654

REFRIGERATING APPARATUS Filed May 17, 1946 r 2 Sheets-Sheet 1 FIG. I

[N VEN TOR.

2 Sheets-Sheet 2 1950 R. s. GAUGLER REFRIGERATING APPARATUS Filed May 17, 1946 FIG. 2

FIG. 3

vide an efficient Patented Aug. 8, 1 950 OFFICE REFRIGERATING APPARATUS Richard S. Gander,

corporation of Delaware Dayton, Ohio, assignor General Motors Corporation, Dayton, Ohio, a

Application May 17, 1946, Serial No. 670,618 8 Claims. ((1281-99) This invention relates to heat transfer apparatus such as, for example, may be for evaporators and absorbers in absorption refrigerating systems.

The eiliciency and eilectiveness of heat transfer units depend largely upon the area of contact of the liquid with the heat transfer walls and the heat transmission between the heat transfer walls and the second fluid. Great difilculties in heat transfer are encountered in absorption refrigerating systems where the flooded type of heat transfer units are not used and where the liquid fills only a small portion of the evaporator and absorber. The efllciency oi. the absorber and evaporator depends largelyupon the area of the liquid surface which is exposed to the circulating gas or vapor and the efllciency of the heat transmission through the walls between the liquid and the external air.

It is an object of my invention to provide an efiicient heat transfer unit employing a plurality of small ducts having simple inexpensive means for producing turbulence and for holding wire gauze in firm direct contact with the entire inner wall surface for holding liquid in contact therewith by capillary action.

It is another object of my invention to proheat transfer unit employing a plurality of small ducts having a plurality of wire gauze sleeves in firm contact with each other and with the walls of the ducts.

It is another object of my invention to provide a simple inexpensive heat transfer unit in which a thin exposed free liquid film of large area is exposed to gas and is also in direct contact with the heat transfer walls.

It is another object of my invention to provide a heat transfer unit having a plurality of parallel paths of liquid flow with a simple inexpensive form of capillary means for distributing the liquid flow to the parallel paths in substantially the proportions desired.

It is another object of my invention to provide a simple inexpensive heat transfer unit containing wire gauze sieeving in which excellent cooling is provided for dissipating heat from the wire gauze.

Briefly, these objects are attained by providing a heat transfer unit formed of five generally horizontal, slightly inclined, tubes connecting with headers at each end and provided with common transverse fins having the major portion of their area beneath the tubes to provide more effective heat transmission between the tubing and the circulating air. Each tube contains three sleeves 01' wire gauze or varying fineness fitting tightly within the tubing and being in flrm contact with each other. These sleeves are supported by a twisted perforated thin metal strip which serves as a core. The liquid is fed substantially equally to each of the sleeving assemblies by a capillary distributor provided in the upper header while a similar capillary device is provided in the lower header for draining the liquid from each of the sleeving assemblies in substantially equal proportion in. the lower header. Gas or vapor preferably is circulated through or drawn from the tubes.

Further objects and advantages oi the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred form of the present invention is clearly shown.

In the drawings:

Fig. 1 is an elevational view of an absorber with the end portions shown in section substantially as lines l--i of Fig. 2; i

Fig. 2 is a sectional view taken along the lines 2-2 of Fig. 1; and

Fig. 3 is a fragmentary view showing the construction of one of the sleeving assemblies.

Rel'erring now more particularly to Figs. 1 and 2, there are shown two supporting brackets 20 and 22 through which extend five slightly inclined til tubes 24, 26, 28, 30 and 32. these tubes each extend into the transverse header 34 to which, through the tubes 36, is fed the weal: liquor from the generator and heat exchanger. The opposite ends of the tubes extend into the lower header 38 from which the enriched liquid is removed through the tube 40 for return through the heat exchanger and fractionator to the generator. When used in a partial pressure absorption refrigerating apparatus, the mixture of the inert gas and refrigerant is fed from the evaporator and heat exchanger through the tube 42 to the lower header 38. The stripped inert gas is removed from the absorber and returned to the evaporator by the tube 44 which connects to the top of the upper header 34.

Each of the tubes preferably containsan identical capillary conduit such as is shown in Fig. 3. The core of the conduit is formed by a twisted perforated steel strip 46 over which is a wire gauze inner sleeve 48 formed of single braided wire sleeving consisting of 48 ends of .010 steel weaving wire with one end up. This first layer is primarily intended for the carrying of the liquid and to hold a large area of freely exposed liquid film.

The second sleeve 50 of wire gauze is designed to provide high capillarity to prime each sleeve At the upper end,

, duits in the five tubes.

upon starting up the apparatus, so that through this layer each sleeving assembly will become entirely. wetted with t e liquid through capillary actioni This second sleeve 50 tightly envelops the inner sleeve 48 and consists of multiple braided wire sleeving having 48 ends of .004 steel weaving wirewith four ends up and eight picks.

The third sleeve 52 of wire gauze tightly envelops the second sleeve 58 and assists in the priming of the assembly; but also serves to carry liquid. This third sleeve 52 consists of single, braided wire sleeving having 48 ends of .008 steel I capillary distributor 58. This capillary distribu tor is formed of an upper roll 60 of wire gauze which is supported in contact with the bottom of each capillary conduit by the inverted channelshaped supports 62 resting upon the bottom of theheader 84. To secure substantially equal distribution of liquid to thisv roll 60 when the liquid level is low, there is provided another stageof liquid distribution by means of the roll 64 of wire gauze which is clamped tothe upper roll 60 by the clamps 66. When the liquid is low, it is fed from the bottom of the header 88 through the lower roll 84 to the two particular points in the upper roll 88 wherein the liquid will be fed substantially uniformly to each'of the capillary con- In the lower header 88. a similar distributor formed of an upper roll 68 and a lower roll I is provided so that the liquid may be drained uniformly from the tubes. After the capillary conduits areinserted in the tubes and the capillary distributors are placed in their proper position within the upper and lower headers 34 and ii, the headers are each closed by a plate, such as the plates I2 and I4, which are welded in place to seal the headers.

I 'As the liquid flows through the capillary conduits from the. upper header 34 to the lower header 38, a mixture of refrigerant and inert gas flows through the interior of the-conduits in the opposite direction. This inert gas is guided by the thin perforated steel strip.46 in a helical path so that it makes-a wiping contact with the liquid on they inner surface of each capillary conduit. The presence of the perforations in the strip 46 promotes free flow of the mixture of inert gas and refrigerant through the interior of the capillary conduits. The size and/or number of perforations may be reduced to increase the wiping contact if the rate of gas, flow is ample. The intimate contact between this mixture and the liquid causes the absorption of the refrigerant by the liquid. This is accompanied by the evolution of considerable heat and to promote this absorption the liquid must be kept cool.

For this purpose the live tubes are efliciently finned through the use of transverse fins 16 which are shared by all of the tubes to make the fins more efiicient. Flanged apertures which receive each of the five tubes are provided about onethird the distance from the top of the fin so that the major portion of their area is beneath the tubes. This improves the efliciency of the fins since the upper portion of each of the fins is less effective because in its upward flow between the fins, the external cooling air is forced to flow around the tubing causing an unequal distribution or air-flow and particularly'reducing the effectiveness of that portion of the fins located directly above each of the tubes. Also this external cooling air which passes by natural convection upwardly between the tubes has had added to it not only the heat transmitted to it by the lower portion of the fins, but also the heat transmitted directly to it by the tubing and the flanges of the fins which raises its temperature and thus lowers the heat transfer differential and rate between the upper portions of the fins Therefore more and the external cooling air. eificient heat transfer for gravity air-flow is provided by these unique fins.

While I have described this apparatus as an absorber, it may also be used as an evaporator by supplying the liquid to be evaporated to the upper header 84 and by removing the vapor produced by the evaporation of the liquid either through-the lowering of the vapor pressure. or through the circulation of stripped inert gas. The apparatus has a relatively large liquid surface exposed within each of the tubes and this liquid surface has good heat transfer through the wire gauze and through the walls of the tubing, and the fins tothe air. The liquid distribution and gas flow is excellent and the apparatus is easy to manufacture and low in cost.

' While the form of embodiment of the invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, as may come within the scope of the claims which follow.

What is claimed is as follows:

1. Heat transfer apparatus including a plurality of tubes, substantially horizontal headers connecting the tubes at the opposite ends thereof, capillary means extending continuously within the tubes from one header to the other header, a unitary horizontal capillary conduit means extending horizontally within one header and contacting one end of each of the capillary means provided within the tubes, and means for feeding a liquid to said capillary conduit meansto distribute the liquid flow to the individual capil-' 'lary means within the tubes.

2. Heat transfer apparatus including a plurality of tubes.substantially horizontal headers connecting the tubes at the opposite ends thereof, capillary means extending continuously with in the tubes from one header to the other header,

a unitary horizontal capillary conduit means extending horizontally within one header and contacting one end of each of the capillary means provided within the tubes, a second capillary con-' duit means having an intermediate portion contacting the bottom of said header and having end portions contacting separated portions of said horizontal capillary conduit means, and means for feeding a liquid to said header to distribute the liquid flow through said second and first conduit means to each of the capillary means.

3. Heat transfer apparatus including a plu-,

rality of tubes, substantially horizontal headers connecting the tubes at the opposite ends thereof, capillary means extending continuously within the tubes from one header to the other header, a separate unitary horizontal capillary means extending horizontally within each header and contacting the adjacent end of each of the capillary means in the tubes, and means for feeding liquid to the capillary conduit means in one header and draining the liquid from the capillary conduit means in the second header.

4. Heat transfer apparatus including a plurality of tubes, substantially horizontal headers connecting the tubes at the opposite ends thereof,

capillary means extending continuously within the tubes from one header to the other header, a separate unitary horizontal capillary means extending horizontally within each header and contacting the adjacent end of each 01 the capillary means in the tubes, a second capillary conduit means in each header having an intermediate portion contacting the bottom of its header and having end portions contacting separated portions of the adjacent horizontal capillary conduit means, and means for feeding liquid to one of the headers and draining the liquid from the second header.

5. Heat transfer apparatus including a plurality of tubes, substantially horizontal headers connecting the tubes at the opposite ends thereof, capillary means extending continuously within the tubes from one header to the other header, a

unitary horizontal capillary conduit means extending horizontally within one header and contacting one end of each of the capillary means provided within the tubes, and means for draining a liquid from said capillary conduit means.-

6. Heat transfer apparatus including a plurality of tubes, substantially horizontal headers connecting the tubes at the opposite ends thereof, capillary means extending continuously within unitary horizontal 6 the tubes from one header to the other header, a

capillary conduit" means extending horizontally within one header and contacting one end of each of the capillary means provided within the tubes, a second capillary conduit means having an intermediate portion contacting the bottom of said header and having end portions contacting separated portions of said horizontal capillary conduit means, and means for draining a liquid from said header.

RICHARD S. GAUGLER.

REFERENCES CITED The following references are of record in the tile of this patent:

UNITED STATES PATENTS Number Name Date 143,534 Shaler Oct. 7, 1873 818,891 Jones et,al., Apr. 24, 1906 1,018,851 Thompson Feb. 27, 1912 1,231,088 Stafford et a1 June 26, 1917 1,962,512 Lenning June 12, 1931 1,983,295 Kohler Dec. 4, 1934 2,198,305 Crawford Apr. 23, 1940 2,307,947 Payne Jan, 12, 1943 2,317,519 Coons Apr. 27, 1943 FOREIGN PATENTS Number Country Date 9,395 Great Britain Apr. 18, 1911 

